Auto Parts: yellow lights, worst case scenario, elbow grease

Question
I have a 97 grand marquies and the headlight covers have turned yellow. Any idea why?  how can i remove and replace these lights if i have to? thanks

Answer
This is not uncommon with clear plastic headlight lenses.  Over time, age, weather, and the good 'ole sun, the plastic deteriorates.  It will start with a slight haze, and eventually get to where you're at now.

If your lenses are hazed on the surface, you can take body finishing sandpaper to it and wet sand it.  Start with ~1,000 grit, then 1,500, then 2,000 running a trickle of water over it as you sand.  Once finished, use some rubbing compound, followed by polishing compound, then finish with your favorite wax.  

Takes a little bit of elbow grease but it can be done and restore your original finish back.

Otherwise, which is what I might be suspecting with your situation, worst-case scenario is the plastic is completely yellowed through.  Sanding and finishing won't fix this problem and you'll need new headlight assemblies.

Hope this helps.

- Brent